ADD file via upload

StudentService.java

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+package com.example.classroomattendance.service;
+
+import com.example.classroomattendance.model.Student;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+@Service
+public class StudentService {
+    private List<Student> students = new ArrayList<>();
+    private Random random = new Random();
+
+    public void addStudents(List<Student> studentList) {
+        students.addAll(studentList);
+    }
+
+    public Student pickRandomStudent() {
+        if (students.isEmpty()) {
+            return null;
+        }
+
+        // 计算所有学生的总权重
+        double totalWeight = 0;
+        for (Student student : students) {
+            totalWeight += getWeight(student);
+        }
+
+        // 随机选择权重范围内的值
+        double randomValue = random.nextDouble() * totalWeight;
+
+        // 选取符合该随机值的学生
+        for (Student student : students) {
+            randomValue -= getWeight(student);
+            if (randomValue <= 0) {
+                return student;
+            }
+        }
+
+        // 防止极端情况下返回最后一个学生
+        return students.get(students.size() - 1);
+    }
+
+    // 获取学生的权重，积分越高权重越低
+    private double getWeight(Student student) {
+        return 1.0 / (student.getPoints() + 1.0); // 防止分母为0
+    }
+
+    public void updateStudentPoints(Long id, double points) {
+        for (Student student : students) {
+            if (student.getId().equals(id)) {
+                student.setPoints(student.getPoints() + points);
+                break;
+            }
+        }
+    }
+
+    public List<Student> getAllStudents() {
+        return students;
+    }
+}